Amplifone image issues - video inside

[jehuie]

Thanks to everyone who helped me get the HV board working. It's all adjusted and seems good to go. Now I'm getting an image that is squished to the bottom half of the screen. Plus I have to turn it up fairly bright to be able to see anything at all and then I get the trace lines showing up too.

Does this just look like a deflection issue to you? Or something else? Here's a link to a very short vid. I didn't want to go too long because of the bright spot on the middle.

http://vimeo.com/25582356

Thanks for looking!

 

[dezbaz]

Turn the brightness down John

Its the 2nd one on the focus block

1. Re-seat and re-flow deflection headers pins
2. Clean pins if corroded
3. Check the 4 deflection transistors using DMM
4. Replace if faulty
5. next . . . depends on results

 

[jehuie]

Turn the brightness down John

Its the 2nd one on the focus block

1. Re-seat and re-flow deflection headers pins
2. Clean pins if corroded
3. Check the 4 deflection transistors using DMM
4. Replace if faulty
5. next . . . depends on results

Ok thanks. Will do. The deflection transistors are brand new though. Just put them in from the Zanen kit so they should be fine. Unless I somehow shorted one or something.

 

[dezbaz]

Ok thanks. Will do. The deflection transistors are brand new though. Just put them in from the Zanen kit so they should be fine. Unless I somehow shorted one or something.

Well, what I said was, check first then replace if failed

The symptoms you shared, point towards the things I listed.

The fact they were new serves as 1 clue only, the other clues can't be ignored

Fault-finding requires all clues to be taken into account

I thought you said you got a fuse blowing, what fuse was it again, I will look into that for you

 

[dezbaz]

Well, what I said was, check first then replace if failed

The symptoms you shared, point towards the things I listed.

The fact they were new serves as 1 clue only, the other clues can't be ignored

Fault-finding requires all clues to be taken into account

I thought you said you got a fuse blowing, what fuse was it again, I will look into that for you

You might of blown one of the regulators on the HV board, so that could cause the collapsed signal to the Deflection

If you left the insulator out, that could of blown the fuse and 1 x reg.

Measure your voltage out and see if you have + & - 24VDC

 

[jehuie]

You might of blown one of the regulators on the HV board, so that would cause the collapsed signal to the Deflection - as it gets its + & - 24V from the HV regulators

If you left the insulator out, that could of blown the fuse and 1 x reg.

Measure your voltage out and see if you have + & - 24VDC

Thanks good idea. And I was definitely going to check the other things you asked me to check as well. When I blew a fuse earlier it was F4 on the deflection board and I figured out that was because I had shorted VR2 to the heat sink. Fixed that and it seems to work other than the current issues. So it sounds like I probably damaged something during that process maybe? I was afraid of that!

 

[jehuie]

Yep, it looks like VR2 is fried since I'm not getting my -24 volts. The display looked the same when I had it working briefly before replacing this so I'm guessing my old one is bad as well.

Do I test it in exactly the same way I would test a regular transistor? I tried...I'm not getting any shorts or opens as far as I can tell but I don't know what the proper readings should be.

And I can't find any locally. I can find the +24V regulator but not the negative one. So I guess I'm back into a waiting period now until I can get one in.

 

[dezbaz]

Yep, it looks like VR2 is fried since I'm not getting my -24 volts. The display looked the same when I had it working briefly before replacing this so I'm guessing my old one is bad as well.

Do I test it in exactly the same way I would test a regular transistor? I tried...I'm not getting any shorts or opens as far as I can tell but I don't know what the proper readings should be.

And I can't find any locally. I can find the +24V regulator but not the negative one. So I guess I'm back into a waiting period now until I can get one in.

Yeah, that's not a transistor.

It takes -30v from the power brick and reduces it to -24V no matter what the load is

Just replace it.

Hey, don't forget to put the insulator in

 

[jehuie]

Turn the brightness down John

Its the 2nd one on the focus block

1. Re-seat and re-flow deflection headers pins
2. Clean pins if corroded
3. Check the 4 deflection transistors using DMM
4. Replace if faulty
5. next . . . depends on results

Ok, finally getting back to this post CAX. I fixed the bad VR and it still looks the same. I re-flowed the deflection header pins and re-seated them. None are corroded at all. Nice and shiny. I pulled all 4 deflection transistors and tested them and they all test good.

Put it all back together and now I'm getting a full picture. But I have to turn it up pretty bright to see it and when I do, it's fuzzy. The focus knob is having absolutely no effect on it. Plus it's showing a bright spot in the middle still. Fortunately, with it so fuzzy I don't think there's much risk of burning the screen but I still don't like having it turned up very bright so I only did for purposes of taking a pic to show you.

Bad connection to the focus maybe?

 

[dezbaz]

Ok, finally getting back to this post CAX. I fixed the bad VR and it still looks the same. I re-flowed the deflection header pins and re-seated them. None are corroded at all. Nice and shiny. I pulled all 4 deflection transistors and tested them and they all test good.

Put it all back together and now I'm getting a full picture. But I have to turn it up pretty bright to see it and when I do, it's fuzzy. The focus knob is having absolutely no effect on it. Plus it's showing a bright spot in the middle still. Fortunately, with it so fuzzy I don't think there's much risk of burning the screen but I still don't like having it turned up very bright so I only did for purposes of taking a pic to show you.

Bad connection to the focus maybe?

The brightness and focus both derive their power from the same place. (focus block divider)

But I must say I had a problem lately where the wire to the focus pin on the block was hanging on by 1 thread. I resoldered easily.

 

[jehuie]

I checked and sure enough one of the wires had come loose from the focus block. Resoldered it and I'm very very close to having this thing right.

Now my problem is that there's still a bright dot in the middle. So if I turn it up bright enough to see the picture, there is a blazing bright dot in the middle wanting to burn my screen. Yikes, immediately turn down.

What could cause this? Everything else looks great as far as I could tell in the very brief moment I tried it.

 

[dezbaz]

I checked and sure enough one of the wires had come loose from the focus block. Resoldered it and I'm very very close to having this thing right.

Now my problem is that there's still a bright dot in the middle. So if I turn it up bright enough to see the picture, there is a blazing bright dot in the middle wanting to burn my screen. Yikes, immediately turn down.

What could cause this? Everything else looks great as far as I could tell in the very brief moment I tried it.

Can you get hold of a HV Probe?

The HV test needs to be done with something disconnected on the HV board, I will have a read and see
if I can find it

Anyone else out there know?

 

[omegaman]

Have you adjusted the color drives on the deflection board? Is the deflection board known to be good when used with another HV board?

Can you measure the B+ voltage, should be around 180 volts DC

 

[omegaman]

Can you get hold of a HV Probe?

The HV test needs to be done with something disconnected on the HV board, I will have a read and see
if I can find it

Anyone else out there know?

It's meant to be set with no image on the screen. You can just put the game into test mode on something like BIP adjust and set it for around 19.5KV.....it doesn't move much under load anyway.

 

[jehuie]

Well I borrowed a HV probe and set the voltage but I suppose it's possible that something has changed since then. Would that cause a dot in the middle like that? I'll check the B+ when I get back home later today.

I hate to have to "borrow" a probe from Fry's again like that.

 

[dezbaz]

I like omegas idea

Adjust the color drives on the Defl. bd

 

[jehuie]

Have you adjusted the color drives on the deflection board? Is the deflection board known to be good when used with another HV board?

Can you measure the B+ voltage, should be around 180 volts DC

Ok, I'll try adjusting those as well. I don't have a spare board to throw in there for testing purposes.

 

[jehuie]

Color drive adjustment has no effect on the bright spot in the middle. B+ is hovering about 185. Is that within tolerance?

Any other ideas?

 

[dezbaz]

So you turned the brightness down to get rid of the dot, and then turned the 3 x color pots up and . . . . . nothing?

Were they at their limit?

 

[omegaman]

185 is fine. If the HV was set too high then your B+ would probably be too high as well, it wouldn't cause a spot in the middle of the screen though.

I take it the game board is known to be good? I had a problem with a Star wars board once where the Z output had gone strange....you couldn't see any images unless the brightness was wound right up.

I would double check everything on the HV board around the focus block wiring, pull all the boots off again and double check the connections, make sure the tube connector pins are good, check continuity back to the HV board and deflection board(colour drives).